Cylinder head arrangement for variable valve actuation rocker arm assemblies

Abstract

A novel cylinder head arrangement for an in-line four cylinder or eight cylinder engine. A modified arrangement allows additional space for installation of wider rocker arm assemblies used for variable valve lift (VVL), cylinder deactivation (CDA) and other types of variable valve actuation (VVA). In one embodiment, cam towers adjacent the end two cylinders are not used. At least one end support is used, which may be an outboard bearing on a camshaft for each end. The wider rocker assemblies may then be installed. In another embodiment, cam towers adjacent the inner two cylinders are eliminated and a single camshaft support piece with a support bearing is installed between the inner cylinders to provide support for the camshafts. The wider rocker assemblies may then be installed on at least one of the middle cylinders. A novel oil control valve operates latches in switching rocker arm assemblies.

What is claimed is: 
     
       1. A system comprising:
 a dual feed hydraulic lash adjuster (DFHLA) configured to provide hydraulic switching fluid to a switching rocker arm, the DFHLA comprising:
 a lower lash compensation port fluidly coupled to engine oil pressure; 
 an upper switching pressure port fluidly coupled to an oil control valve (OCV) to provide hydraulic switching fluid to the switching rocker arm at a variable pressure; and 
 
 wherein a latch pin in a first position allows lost motion movement between an inner arm and an outer arm of the switching rocker arm about a pivot axle coupling the inner arm and the outer arm, and wherein the latch pin in a second position prevents lost motion movement between the inner arm and the outer arm of the switching rocker arm about the pivot axle; 
 the switching rocker arm further comprising a pivoting valve pad that contacts and drives a valve stem, wherein the pivoting valve pad is mounted on the pivot axle, and wherein lips formed on the inner arm restrict the pivoting valve pad from rotating about the pivot axle; 
 wherein the latch pin is responsive to the hydraulic switching fluid to move between the first position and the second position, and 
 wherein the inner arm comprises an inner arm sloped surface and the latch pin comprises a latch pin sloped surface, wherein the inner arm sloped surface and the latch pin sloped surface are configured to provide a smooth latch movement when the inner arm sloped surface contacts the latch pin sloped surface. 
 
     
     
       2. The system of  claim 1 , wherein the latch pin is biased to the first position, wherein the OCV controls hydraulic pressure to a low pressure value when the latch pin is in the first position, and wherein the OCV controls hydraulic pressure to a high pressure value to move the latch pin to the second position. 
     
     
       3. The system of  claim 2 , further comprising an upper gallery fluidly coupling the OCV to the upper switching pressure port, and a passive air bleed port fluidly coupled to the upper gallery. 
     
     
       4. The system of  claim 2 , wherein the low pressure value comprises a value between 0.2 bar (20,000 Pa) and 0.4 bar (40,000 Pa). 
     
     
       5. The system of  claim 1 , wherein the latch pin sloped surface is on a non-latching side of the latch pin. 
     
     
       6. The system of  claim 1 , wherein a first torsion spring is mounted on a first side of the outer arm and a second torsion spring is mounted on a second side of the outer arm, the first torsion spring and the second torsion spring in contact with a cam-contacting member. 
     
     
       7. A switching rocker arm responsive to an oil control system to provide variable valve timing, the switching rocker arm comprising:
 an outer arm comprising first and second outer side arms; 
 an inner arm comprising first d second inner side arms and a cam-contacting member configured for transferring motion from a lift lobe of a cam to the switching rocker arm, the inner arm disposed between the first and the second outer side arms and the cam-contacting member disposed between the first and second inner side arms; 
 a pivot axle securing the inner arm to the outer arm, the pivot axle configured to permit pivoting movement of the inner arm relative to the outer arm about the pivot axle; 
 at least one biasing spring secured to the outer arm, the at least one biasing spring in contact with the cam-contacting member; 
 a dual feed hydraulic lash adjuster (DFHLA) configured to provide hydraulic switching fluid to the inner arm, wherein the DFHLA comprises a lower lash compensation port fluidly coupled to engine oil pressure, and an upper switching pressure port fluidly coupled to an oil control valve (OCV); 
 a latch for selectively securing the inner arm relative to the outer arm thereby selectively, permitting lost motion movement of the inner arm relative to the outer arm about the pivot axle, and wherein a position of the latch is responsive to the hydraulic switching fluid; and 
 an inner arm sloped surface of the inner arm and a latch sloped surface of the latch configured to provide a smooth latch movement when the inner arm sloped surface contacts the latch sloped surface; 
 a pivoting valve pad that contacts and drives a valve stem, wherein the pivoting valve pad is mounted on the pivot axle, and wherein lips formed on the inner arm restrict the pivoting valve pad from rotating about the pivot axle. 
 
     
     
       8. The switching rocker arm of  claim 7 , wherein the latch comprises a surface for orienting the latch and preventing rotation of the latch. 
     
     
       9. The switching rocker arm of  claim 7 , wherein the lost motion movement of the inner arm provides a low lift motion of a valve of an engine providing the engine oil pressure. 
     
     
       10. The switching rocker arm of  claim 7 , wherein the cam-contacting member comprises a bearing mounted on a bearing axle. 
     
     
       11. The switching rocker arm of  claim 10 , wherein the first and second outer side arms each comprise a pivot axle aperture, a bearing axle slot, a clip aperture, and a spring mount. 
     
     
       12. The switching rocker arm of  claim 7 , wherein the cam-contacting member is mounted on a bearing axle, wherein the at least one biasing spring comprises first and second torsion springs mounted on first and second sides of the outer arm, the first and second torsion springs in contact with the cam-contacting member. 
     
     
       13. The switching rocker arm of  claim 7 , wherein the pivot axle and the latch are positioned at opposing ends of the switching rocker arm. 
     
     
       14. The switching rocker arm of  claim 7 , wherein the latch is biased to a first position, wherein the OCV controls hydraulic pressure to a low pressure value when the latch is in the first position, and wherein the OCV controls hydraulic pressure to a high pressure value to move the latch to a second position. 
     
     
       15. The switching rocker arm of  claim 14 , further comprising an upper gallery fluidly coupling the OCV to the upper switching pressure port, and a passive air bleed port fluidly coupled to the upper gallery. 
     
     
       16. The switching rocker arm of  claim 14 , wherein the low pressure value comprises a value between 0.2 bar and 0.4 bar. 
     
     
       17. The switching rocker arm of  claim 7 , wherein the latch sloped surface is on a non-latching side of the latch. 
     
     
       18. A method for operating an oil control system for a latch pin of a variable valve actuation system, the method comprising:
 providing engine oil pressure to a lower lash compensation port of a dual feed hydraulic lash adjuster (DFHLA); 
 operating the latch pin of a switching rocker arm between a first position allowing lost motion movement between an inner arm and an outer arm of the switching rocker arm about a pivot axle coupling the inner arm and the outer arm, and a second position preventing lost motion movement between the inner arm and the outer arm of the switching rocker arm about the pivot axle; and 
 wherein operating the latch pin comprises providing one of a low pressure value or a high pressure value to an upper switching port of the DFHLA, thereby providing hydraulic switching fluid to the switching rocker arm, 
 engaging an inner arm sloped surface of the inner arm with a latch pin sloped surface of the latch pin to smoothly disengage the inner arm and the latch pin; and 
 driving a valve stem through contact with a pivoting valve pad, wherein the pivoting valve pad is mounted on the pivot axle, and wherein lips formed on the inner arm restrict the pivoting valve pad from rotating about the pivot axle. 
 
     
     
       19. The method of  claim 18 , wherein one of the first position or the second position comprises a switched position, and wherein the operating the latch pin comprises providing the high pressure value to engage the switched position. 
     
     
       20. The method of  claim 19 , further comprising biasing the latch pin to the other one of the first position or the second position, and providing the low pressure value to disengage the latch pin. 
     
     
       21. The method of  claim 18 , further comprising bleeding air from an upper gallery fluidly coupling at least one of the low pressure value or the high pressure value to the upper switching port. 
     
     
       22. The method of  claim 18 , wherein the low pressure value comprises a value between 0.2 bar and 0.4 bar. 
     
     
       23. The method of  claim 18 , further comprising, providing a torsion force produced by a first torsion spring and a second torsion spring mounted on the outer arm to a cam-contacting member of the switching rocker arm. 
     
     
       24. The method of  claim 18 , wherein the latch pin sloped surface of the latch pin is on a non-latching side.